Lamp arrangement employing a resonant circuit formed from an autotransformer and a capacitor where the capacitor is switched out of the resonant circuit and into a power factor correcting circuit when the ignition of the lamp is sensed

Abstract

An improved fluorescent ballast circuit for 277 volt commercial application is disclosed utilizing a resonant circuit mechanism to generate high open circuit voltage (OCV) during lamp starting. The result is an energy efficient effective lighting system for commercial buildings.

What is claimed as new and desired to be secured by Letters Patent of the United States is: 
     
       1. An improved energy efficient ballast circuit for a commercial fluorescent lighting system using a standard commercial high voltage feed of between 220 and 347 volts for operating a high wattage, high lumen per watt fluorescent lamp, said circuit comprising: starter means for preheating said lamp and for providing low energy high voltage ionization pulses, said starter means including a positive temperature coefficient resistor;   resonant circuit means including an inductance means and a capacitance means for generating an open circuit voltage significantly higher than said high voltage feed wherein said open circuit voltage is sufficient to start-up and stabilize said lamp;   relay means, responsive to a full current draw by said lamp, to clamp off said starter means and to transfer said capacitance means from said resonant circuit whereby said transferred capacitor means acts as a power factor corrector capacitance during normal lamp operation.   
     
     
       2. The ballast circuit according to claim 1, wherein said lamp is at least a 96 watt fluorescent lamp which provides between 80 and 84 lumens per watt. 
     
     
       3. The ballast circuit according to claim 1, wherein said capacitance means includes an 8 microfarad capacitor and wherein said reactor means is 230 ohm, 0.9 amp, 0.22 henry inductance and wherein said resonant circuit means provides an open circuit voltage of approximately 436 volts RMS during lamp ignition and starting. 
     
     
       4. The ballast circuit according to claim 1, wherein said high voltage ionization pulses are at least 3 kilovolts. 
     
     
       5. The ballast circuit according to claim 1, wherein said relay means includes a DC time constant transfer circuit to sense the "on" or "off" status of said lamp. 
     
     
       6. The ballast circuit according to claim 1, wherein said relay means includes a relay coil responding to the status of said lamp to provide a signal to control a switch for said transfer of said capacitance means from said resonant circuit in order to provide said power factor correction during normal operation of said lamp. 
     
     
       7. An improved energy efficient ballast circuit for a commercial fluorescent lighting system using a standard high voltage commercial feed between 220 and 347 volts for operating a high wattage, high lumen per watt fluorescent lamp, said circuit comprising: a filament preheat circuit means including a positive temperature coefficient preheat resistance connected in series with a high voltage standoff RFC (radio frequency choke) for preheating filaments of said lamp to emmissive temperatures;   current relay means connected in series with said preheat means;   resonant circuit means including an inductance and a capacitance means for generating an open circuit voltage which is substantially at least 1.5 times larger than said high voltage feed; and   means for switching, in response to said current relay, said capacitance means from said resonant circuit means to form a power factor correction capacitor circuit during normal lamp operation.